Various detachable hinge devices have provided a capability for detaching or separating the hinge flaps one from the other so the underlying structures to which they respectively attach may be separated or disassembled without need to remove one or both of the hinge flaps from those structures. However, in order to attach one flap to the other or to disconnect them, it has usually been necessary to skew one flap with respect to the other or to displace one flap longitudinally of the other. Both of these actions may require considerable or unavailable workspace to accomplish separation of the underlying structures. With other detachable hinges, the flaps may undesirably be separable, e.g., at particular rotational positions of the flaps even though apparently connected, for example as in U.S. Pat. Nos. 782,428 to Struble and Cain and 2,794,208 to Scroggins. Still other detachable hinge devices have required such atypical construction as to give the hinge a non-conventional appearance, for example by auxilliary strap attachments connecting between the opposing hinge flaps as disclosed in U.S. Pat. No. 3,805,325 to Lee. Such externals may also cause airflow turbulence in aircraft use. In cases where the hinge pin must be removed to allow the flaps or plates to be separated, typically, an exposed portion of the hinge pin must be permanently crimped to prevent its accidental removal so requiring damaging or destruction of the pin in order to release it. The invention herein overcomes the above and other prior art disadvantages.